Recently, the size of storage devices such as hard disk drives (HDDs) and solid state drives (SSDs), which are mounted in a storage apparatus, has been changing from 3.5 inches to 2.5 inches. Along with the change of the storage device size, a structure for mounting storage devices in high density in a storage apparatus has been realized.
For example, Japanese Patent Application Laid-Open (Kokai) Publication No. 2006-24283 and Japanese Patent Application Laid-Open (Kokai) Publication No. 2006-73045 disclose rack-mount-type disk array apparatuses that enable high-density mounting by retaining a plurality of disk drives in upright positions in a housing unit (chassis) and also enable maintenance and replacement of disk drives by pulling out the housing unit from the front side of the rack in a horizontal direction.
Furthermore, Japanese Patent Application Laid-Open (Kokai) Publication No. 2007-35173 discloses a disk array apparatus that includes rows of disk drives mounted in an air flow travelling direction and a chassis that houses the disk drives; and the air flow passes through a passage between a top face of the disk drives and an top face inner wall of the chassis; and insufficient cooling of the disk drives due to high-density mounting of the disk drives is compensated for by providing a dam for narrowing down the air flow at a position downstream of the passage above the disk drives.
Furthermore, a data storage system utilizing SSDs, which emulate HDDs, as storage drives is disclosed in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2009-536767.